Consider using es-abstract

[ljharb]

Hi!

I've built a library, es-abstract. I use it in all my polyfills/shims so that the implementations can match the spec text as exactly as possible.

If you used it in the Temporal polyfill, then you'd be able to largely implement it in exact terms of the spec text. This has exposed spec bugs in proposals in the past.

For abstract operations that this proposal changes or adds, you'd want to implement them locally for the time being, but in a way where they can be seamlessly switched out for an es-abstract implementation once the proposal lands in the spec.